nav a {
  text-decoration: none;  /*PM: sorgt dafür, dass Links nicht unterstrichen sind*/
}
nav > ul > li {
  /* float: left; */
  display: inline-block;

}
 nav > ul > li > a { /*PM: Oberste Ebene des DropDown */
  display: block;
  padding: 2px 5px;
}
.dropdown > a { /*PM: Oberste Ebene des DropDown */
  z-index: 2;
  color: #000;
}
.dropdown > ul {
  z-index: 1;
  padding: 0;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
}
.dropdown > ul > li {
  width: 100%;
  display: table;
}
.dropdown > ul > li > a {  /*PM: Aussehen des aufgeklappten Eintrags*/
  height: 40px;
  padding: 0 15px;
  display: table-cell;
  white-space: nowrap;
  vertical-align: middle;
  background-color: #FFF;
}
/* .dropdown > ul > li > a:focus, .dropdown > ul > li > a:hover {
  background-color: #B71C1F;
  color: #FFF;
} */

@media (max-width: 400px) {
  nav > ul > li {
    width: 100%;
    border-right: 0 !important;
  }
  nav > ul > li:not(:last-child) > a {
    border-bottom: 1px solid #444;
  }
  nav > ul > li:not(:last-child) > a:focus {
    border-bottom-color: #ddd;
  }
  nav > ul > li.dropdown > ul {
    box-shadow: none;
  }
}

.dropdown {
  position: relative;
}
@media (min-width: 400px) {
  .dropdown > ul {
    left: 0;
    top: 100%;
    opacity: 0;
    position: absolute;
    visibility: hidden;
    transition: all .1s ease-in-out;
  }
 .dropdown > a:focus + ul {
    opacity: 1;
    visibility: visible;
  }
  .dropdown:hover > ul {
    opacity: 1;
    visibility: visible;
  }
}
@media (max-width: 400px) {
  .dropdown > ul {
    opacity: 0;
    max-height: 0;
    visibility: hidden;
    padding: 0 !important;
    transition: max-height .3s linear;
  }
  .dropdown > a:focus + ul {
    opacity: 1;
    padding: 15px;
    overflow-y: auto;
    max-height: 500px;
    overflow-x: hidden;
    visibility: visible;
  }
}